Method for activating a vehicle function and associated activation device

A method for activating a vehicle function using an activation device intended to be fitted on board a vehicle, comprising at least two ultra-wideband transceivers located on either side of an opening element and on the same side of the vehicle, separated by a predetermined distance and capable of communicating with a portable user appliance, wherein the two transceivers are adapted so that they can communicate with each other via ultra-wideband communication, the method comprising:

• a) transmitting waves by at least one first transceiver;
• b) receiving reflected waves originating from the portable appliance and determining a time of flight of the waves;
• c) computing a radius of a circle centered around the first transceiver as a function of the time of flight, and determining a perimeter of said circle on which the portable appliance may be located;
• d) receiving reflected waves originating from the second transceiver;
• e) comparing a profile of the reflected waves received over time with a predetermined received wave profile;
• and
• f) detecting a presence in a predetermined area around the two transceivers as a function of the result of the comparison;
• i) computing, if a presence is detected, a distance between the second transceiver and said presence;
• ii) locating the portable appliance as a function of the computation of an intersection between said computed distance and the previously determined perimeter;
• and
• iii) activating the vehicle function as a function of said location.